Feasibility of Implantable Myoelectric Sensors to Control Upper Limb Prostheses

The study assesses the feasibility of an advanced prosthesis control system aimed at development of a more intuitive and functional prosthetic device. Tiny (2.5 mm by 16 mm) Implantable Myoelectric Sensors (IMES) will be implanted into the residual forearm muscles of three transradial amputee subjects. These devices wirelessly transmit electrical muscle signals to an electromechanical prosthetic wrist and hand.

Following a two-week recovery from implantation of six to eight IMES into residual forearm muscles, subjects will initiate seven months of training. Subjects first train for approximately a month using a bench-top IMES system. When they receive their custom-fit IMES Prosthesis (including electromechanical wrist and hand) subjects initiate six months of additional training. Subjects will then be given the option to use the IMES Prosthesis for another sixteen months. The usability and functionality of the prosthetic system will be evaluated throughout the study.

Inclusion criteria

• Patient is a health care beneficiary at the Walter Reed National Military Medical Center.
• Patient has transradial amputation with one-third or greater residual forearm length as determined by the contralateral side.
• Patient's residual forearm anatomy (based on number and size of residual muscles) will support the implantation and control of at least six IMES (in the opinion of the Investigator). This criterion will be verified during a study-specific screening test.
• Patient is age 18 or above.
• Patient can speak and comprehend English.
• Patient is willing and capable of providing informed consent.
• Patient has undergone amputee rehabilitation, including being trained to wear and use a body-powered and myoelectric prosthesis.
• Patient reports wearing an upper limb prosthesis at least two hours per day.
• Unilateral amputation with preserved function of the non-amputated arm; preserved function is investigator opinion as to whether the patient:

• has the ability to independently don and doff a prosthesis,
• has enough dexterity in the non-amputated arm to attach and detach the Prosthetic Control Interface (PCI) cable and operate the PCI power switch,
• has the dexterity to remove and replace the PCI battery.
• Patient is willing and capable of having EMG needles inserted into the forearm.
• In the opinion of the Investigator, patient is cognitively capable of operating an IMES Prosthesis.
• Patient is willing to comply with a wearing schedule for the investigational device.
• Patient is willing and capable of travelling to the investigational site for study visits outlined in this protocol.

Exclusion criteria

• Patient is less than three months from amputation surgery or major injury of the target residual limb.
• Patient has major injury proximal to the level of amputation.
• In the opinion of the Investigator, patient is prone to skin breakdown in the target residual limb.
• Known nerve transection or palsy that may cause de-innervation of muscles in the target residual limb.
• Known genetic neuromuscular disorder (e.g. multiple sclerosis, myasthenia gravis, muscular dystrophy).
• Patient has a bleeding or clotting disorder.
• Bilateral upper extremity amputation.
• Patient has a major psychological disorder such as poorly controlled PTSD, schizophrenia, or paranoia such that cooperative status is inconsistent.
• Patient has an active implant (e.g. pacemaker, implanted cardiac defibrillator [ICD], neurostimulator, drug infusion device).
• Patients having any metal fragments or metal implants (e.g. orthopedic hardware) located within the residual forearm are excluded. The absence of metal shall be confirmed by an x-ray of the entire affected arm.
• Patients having metal in the affected upper arm will be considered on a case-by-case basis. An x-ray of the entire affected arm shall be provided to the Sponsor who will assess potential interaction of the metal with the Coil's magnetic field.
• Patient has a history of adverse reactions to anesthetic agents.
• Patient has recently or is currently participating in research that may influence response to either study intervention, or be harmful to the subject in any way.
• A female patient who is pregnant, nursing, or planning to become pregnant during the course of the study.
• In the opinion of the Investigator, the subject is not a suitable candidate for the study, for any reason such as residual limb infection, significant pain, significant proximal nerve injury or soft tissue damage, significant scarring, or poor health of the skin envelope.